(a) Field of the Invention
The present invention relates to an inflatable two-layer fabric, more particularly to an inflatable two-layer fabric that can be used for car airbags or life jackets.
(b) Description of the Related Art
An inflatable fabric can be used for car airbags and life jackets. The inflatable fabric is especially useful for a side curtain airbag which is unfolded at the side windowpane to protect the passenger's head from being hurt by colliding with the windowpane or other structures. It is useful because the fabric should be at an inflated state for over 5 seconds if the car rolls over.
In general, methods for manufacturing inflatable fabrics for car airbags are classified into: 1) a method of sewing, fusing, or adhering two fabrics; and 2) a method of using a two-layer fabric wherein the two layers are partly crossed by an attachment point.
However, the first method requires additional sewing, fusing, or adhering procedures in addition to preparing two fabrics, resulting in complicated procedures and increasing manufacturing costs.
To solve this problem, the second method has been recently proposed.
An inflatable fabric has two separate fabric layers and an attachment point between said fabric layers. The fabric enclosed by the attachment point strongly interlocks the two layers when each single layer inflates rapidly, so that no air leaks out.
Methods to form an attachment point in said inflatable two-layer fabric has been proposed by U.S. Pat. Nos. 6,220,309, 5,098,125, 5,011,183, and 5,603,647.
U.S. Pat. No. 6,220,309 discloses a two-layer fabric whose separator area is formed of a plain weave and whose attachment area is formed of a 2/2 basket weave; U.S. Pat. Nos. 5,098,125 and 5,011,183 disclose a two-layer fabric whose separator area is formed of a plain weave and whose attachment area is formed of a 2/2 basket or 3/3 basket weave, a 1/2 twill or 1/3 twill weave, or a 5 harness satin; and U.S. Pat. No. 5,603,647 discloses a two-layer fabric whose separator area is formed of a plain weave, a basket weave, or a twill weave, and whose attachment area is formed of a 3/3 basket weave. Here, the separator area refers to the area in the two-layer fabric where the two fabric layers (upper layer and lower layer) are separated from each other, so that the two-layer fabric may inflate by air, etc. The attachment area refers to the area where the two separated fabric layers are attached to each other.
The above-mentioned two-layer fabrics mainly utilize attachment areas formed of a 3/3 basket weave or a 2/2 basket weave. However, if they are used alone, air may leak out at the attachment area when the two separated layers inflate.